Cinnabar

Cinnabar is a member of sulfide minerals with chemical formula is mercury sulfide, HgS. It is bright scarlet to deep grayish red in color. It is the major source of mercury. Crystals are uncommon but when found they are rhombohedral, tabular, or prismatic. It usually occurs as massive or granular aggregates, but sometimes powdery coatings. Cinnabar is often found with other minerals such as stibnite, pyrite, and marcasite in veins near recent volcanic rocks. It is also found around hot springs. Cinnabar is believed to have been mined and used in Egypt in the early 2nd millennium BCE. It has also been mined for at least 2,000 years at Almadén, Spain. This site still yields excellent crystals.

Name: From the Medieval Latin cinnabaris, traceable to the Persian zinjifrah, apparently meaning dragon’s blood, for the red color.

Association: Mercury, realgar, pyrite, marcasite, stibnite, “opal”, “chalcedony”, barite, dolomite, calcite.

Chemistry: Essentially pure HgS.

Polymorphism & Series: Trimorphous with metacinnabar and hypercinnabar.

Crystallography: Rhombohedral; trigonal-trapezohedral. Crystals usually rhombohedral, often in penetration twins. Trapezohedral faces rare. Usually fine granular massive; also earthy, as incrustations and disseminations through the rock.

Diagnostic Features: Recognized by its red color and scarlet streak, high specific gravity, and cleavage.

Chemical Properties of Cinnabar

Chemical Classification	Sulfide mineral
Chemical Composition	HgS

Physical Properties of Cinnabar

Color	Cochineal-red, towards brownish red and lead-gray
Streak	Scarlet
Luster	Adamantine to dull
Cleavage	Perfect Perfect {1010}
Diaphaneity	Transparent in thin pieces
Mohs Hardness	2.0–2.5
Specific Gravity	8.176
Diagnostic Properties	Association with volcanic activity.
Crystal System	Trigonal
Tenacity	Sectile
Fracture	Irregular/Uneven, Sub-Conchoidal
Density	8.176 g/cm3 (Measured) 8.20 g/cm3 (Calculated)

Optical Properties of Cinnabar

Type	Anisotropic
Anisotropism	High
Optic Sign	Uniaxial (+)
Birefringence	δ = 0.351
Relief	Very High

Occurrence

Cinnabar is a hydrothermal mineral that precipitates from ascending warm waters and vapors as they flow thru fractured rocks. It forms at shallow depths wherein temperatures are less than approximately 200 stages Celsius. It normally bureaucracy in rocks surrounding geologically latest volcanic hobby however can also form close to hot springs and fumaroles. Cinnabar precipitates as coatings on rock surfaces and as fracture fillings. Less frequently, cinnabar can be deposited inside the pore spaces of sediments. It is usually big in dependancy and is hardly ever discovered as nicely-fashioned crystals. Other sulfide minerals are typically discovered related to cinnabar. These can consist of pyrite, marcasite, realgar, and stibnite. Gangue minerals associated with cinnabar include quartz, dolomite, calcite, and barite. Small droplets of liquid mercury are from time to time present on or close to cinnabar.

Uses Area

The only important ore of mercury.
Its use as a pigment, gem, and ornamental carving material has declined due to toxicity

Distribution

The most common ore of mercury world-wide, so only a few localities for exceptionally abundant or well-crystallized material can be mentioned.

In the USA, in California, notably at New Almaden, Santa Clara Co. and New Idria, San Benito Co.; in Texas, at Terlingua, Brewster Co.; in Nevada, at the Cahill mine, Poverty Peak district, Humboldt Co., and near Lovelock, Pershing Co.
At Charcas, San Luis Potosı, Mexico.
In Spain, from Almaden, Ciudad Real Province, and Mieres, Asturias.
At Hydercahn, in the Fergana basin, Kazakhstan.
From Tongrin, Wanshanchang, and elsewhere in Guizhou Province, and in exceptional twinned crystals from the Tsar Tien mine, Hunan Province, China.
As fine crystals at Mount Avala, near Belgrade, Serbia.
From Idrija (Idria), Slovenia.

References

Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
Mindat.org. (2019). Cinnabar: Mineral information, data and localities.. [online] Available at: https://www.mindat.org/min-727.html [Accessed 4 Mar. 2019].